For safety reasons, zero turning radius (ZTR) mowers of a certain weight may be provided with some form of rollover protection structure, or ROPS, to prevent the vehicle from crushing the operator if it accidentally rolls over. The ROPS should be capable of supporting the forces generated by the weight of the vehicle in the event of a rollover, maintaining free space for the operator to reduce the danger of injury.
The ROPS may be steel tubing with a generally rectangular cross section, having lower legs that may be welded to brackets and/or bolted to the vehicle frame. A ROPS is designed to absorb energy from the weight of the vehicle, and the brackets or lower section of the ROPS may transfer energy to the vehicle frame. The ROPS also may include an upper portion or crossbar with an inverted U-shape located above the head of the operator.
Some ROPS may have a single pivot and may be folded down from a raised or upright position to a lowered or folded down position. For example, U.S. Pat. Nos. 4,949,991; 5,503,430; 5,779,272; and 5,839,758 relate to ROPS that can be moved from a raised or upright position to a lowered or folded down position. The hinge assembly where the ROPS structure folds may be a rotary style joint that may be easily and quickly operated between the raised and lowered positions without tools. Retention or locking pins (e.g., rods, clips or bolts) may be inserted through holes or slots in the upper and lower ROPS, and/or through holes in hinge plates joining the upper and lower ROPS.
Some zero turning radius (ZTR) mowers have a single pivot ROPS in which the upper portion may be pivoted rearwardly and downwardly behind the rear mounted engine. Pivoting the upper portion of the ROPS to the lowered position behind the engine may reduce the height of the ZTR mower but increase its length, requiring a longer shipping container or crate, and requiring additional length for storage or transportation of the ZTR mower on a truck or trailer. If part of the ROPS extends out of the container, there also may be a risk of shipping damage. Some ZTR mowers have a single pivot ROPS in which the upper portion may be pivoted forwardly to a lowered position in front of the operator station. For example, U.S. Pat. Nos. 9,511,735 and 9,616,837 show ROPS that can fold forward for shipping. In the lowered position, the upper portion of the ROPS may rest on or above the operator seat. There is a need for a ROPS that may be pivoted further below the operator seat, so the ZTR mower may fit in even smaller shipping containers or crates, and achieve higher shipping density.
Conventional folding ROPS on ZTR mowers may be secured in either of the raised or lowered positions by inserting one or more locking pins through holes in the upper ROPS tubing walls and hinge plates respectively to secure the upper portion. The pins may be rods, clips or bolts. Some ROPS on ZTR mowers have spring loaded knobs which must be pulled out and rotated 90 degrees to engage or disengage the pins from the holes. A ZTR mower with a folding ROPS is needed that is relatively simple to operate and helps reduce or minimize use of the ZTR mower while the ROPS is not secured in an operating position.